Electric fuse



Feb. 11, 1941. s. R. SMITH, JR

ELECTRIC FUSE Filed Jan. 14. 1939 INSULATION INSULATION 1T1 VEYTbOT": S'nchqey R. Smith Att orn e y.

Patented Feb. 11, 194i PATENT OFFICE ELECTRIC FUSE Sidney R. Smith, Jr., Pittsll eld, Mass., assignor to General Electric Company, a corporation of New York Application January 14,

1939. Serial No. 350,993

4 Claims. (01. zoo-11?)v vThe present invention relates to electric fuses and more particularly to so-called secondary fuses which are suitable for such purposes as protection of transformers from secondary faults,

5 isolation of service-entrance faults, and banking of transformer secondaries.

The invention has for a principal object the provision of an improvedand simplified form of secondary fuse which requires no separate insulating support and is adapted for outdoor instal lations; such as oil-overhead distribution lines in conjunction with strain insulatorsiawhich has low initial cost and is easy to install and refuse and which functions upon'fuse operation to 'give 5 a readily observable indication of the operated- A more specific object of the invention is the provision of simple and low cost means for sus pension mounting of a common form of expulsion I fuse holder directly on conductors-of an overhead electric line.

Other objects and the details of that which I consider to be novel and my invention will become apparent from the following description 5 and the claims appended thereto, taken in conjunction with the accompanying drawing in which Fig. 1 shows a fuse device constructed in accordance with the present invention and an exemplary'method of installing the fuse device 0 on an electric line, whileFlg. 2 is a detail perspective view of certain of the elements of the device of Fig. l.

It is contemplated that different forms of fuse holders may be employed in the construction of a fuse device in accordance with the present invention, but in the preferred" embodiment illustrated there is employed a common form of fuse 'holder of simple and inexpensive design, readily available on the market, and having already 4 widely accepted usage in other types of fuse cutouts; minisa particularly advantageous feature of my invention, since it makes possible reduction in variety and number of parts carried in stock for protection and line maintenance purposes, with resultant substantial savings in' expense to power companies. Such a fuse holder, as illustrated, comprises an expulsion tube III, of fibrous or other suitable insulation material, one end of which is closed by a metallic terminal cap I i screw-threaded thereon and the other end of which tube is open for expulsion of gases therefrom. The fuse holder is adapted to be fused with common forms of cable type fuse links having the desired current interrupting ratings.

One end of such fuse link, installed in tube ll,

is electrically connected with terminal cap H in a manner well known in the art, while the other end, orflexible cable extension, indicated at l2, projects from the open end of the tube for connection purposes.

1 In the exemplary installation illustrated, which -ma'y--be, at a line sectionalizing point, the fuse device of:the present invention is employed in conjunction with a common form of strain insulator, designated I 3, which serves to join mechanically in a well known manner, two line conductors II and I5. For suspension mounting of the fuse holder on the line conductors, I have provided aupair of electrically conductive articulated mounts. One of these mounts includes a metallic strap 16, secured to fuse tube It adlacent the open end of the tube, and a .relatively stiff metallic connector or hanger'element l1 pivotaily' joined to strap l6 by means'of a bolt I8. Hingedly mounted on element IT, by means of lugs 20, is a flanged clamping plate 2| with a screw-threaded stud 22 and a wing-nut 22 for supporting conductor, such as line conductor IS. The other articulated mount includes a metallic strap 25,-secured to terminal cap Ii, and a relatively stifl metallic connector element 26 pivotally joined to strap 25 by means of a bolt 21. Hanger element 26, similarly to element IT, hasa clamping plate with a screw-threaded stud 22 and a wing-nut 22 for clamping attachment to a bared portion of a second supporting conductor, such as line conductor I. As will be evident from the drawing, the right-hand conductive mount, including element H, is considerably longer than the left-hand mount, including element 2'. This serves the important purpose of supporting fuse tube l-ll tilted at an angle to the horizontal with the open end of the tube lowermost so that water will not collect in the tube to cause deterioration and possible failure of the fuse link therein. The articulated joints between the elements of the conductive mounts permit adjustment of the positional relationship between the conductor clamps, including plates 2|, of the two mounts, and thereby' provide for flexibility in mounting of the fuse device softhat the device. may be accommodated to various sizes of strain insulators and spacings of supporting conductors.

The connector element ll of the right-hand mount has a thumb-screw terminal clamp, indicated at .20, for attachment of fuse link extension l2 thereto. Element I! also carries a resilient flipper arm 3|, one end of which is afiixed to element H by means of a slot 32 and a I clamping attachment to a bared portion of a U ily observable indication of fuse operation, as

shown in Fig. 2.

V For refusing, it is necessary only to detach the clamp of the left-hand mount from conductor H and to unscrew cap ll, replace the blown fuse link in the fuse tube with a new fuse link, connect the cable extension of the new fuse link' with terminal clamp 30, engage hook 34 with the cable extension, and then re-attach the lefthand mount to conductor H. The construction and method of mounting of the fuse device insures safety in refusing since a fuse link cannot be inserted in the fuse tube unless at least one of the conductive mounts is detached from its supporting conductor.

From the foregoing it will be seen that I have provided a simple and inexpensive fuse device which requires a minimum of special parts, is easy and safe to install and refuse, and which upon fuse operation gives a readily observable indication while facilitating the circuit interrupting process by drawing out the arc within the fuse tube. Thus my improved fuse device is particularly advantageous for applications where it is desired to provide reliable fused protection at minimum cost. It is contemplated that there will suggest themselves to those skilled in the art modifications of certain details of the illustrated fuse device, such as to adapt the device for various installation conditions encountered. Also, the invention is'not limited to the particular forms of fuse link flipper arm and line conductor engaging clamps illustrated in the drawing. Hence it is intended that such modifications as do not depart from the true spirit of the invention shall come within the scope of the appended claims.

"What I claim as new and desire to secure by Letters Patent of the United States is:

l. A line suspension fuse comprising an insulating fuse tube closed at one end by a removable metallic terminal cap and open at the other end, a conductive mount clamped on said terminal cap. a second conductive mount clamped on said tube adjacent the open end thereof, said mounts having clamps for attachment thereof respectively b0 electric line conductors for suspension mounting of said tube directly on such conductors, and a terminal clamp on said second mount for securing thereto one end of a link extending out of the open end of said tube.

2. A line suspension fuse adapted to be supported by and electrically to connect two line conductors which are mechanically joined by a strain insulator or the like; said fuse comprising a fuse holder including an insulating fuse tube having at least one end open, a first conductive mount secured to said holder adjacent said one end of said tube and having a terminal clamp for securing thereto one end of a fuse link extending out of said one end of the tube, a second conductive mount secured to said holder adjacent the other end of the tube, and means to effect electric connection betweemsaid second mount and fuse link in-the tube, said mounts having clamping means for clamping attachment thereof respectively to conductors for supporting the fuse holder, and at least one of said mounts including a plurality of relatively stiff elements articulated for relative movement so as to provide for variation of the positional relationship between the said conductor clamping means of the two mounts. 3. A line suspension fuse comprising a fus holder including a fuse tube open at one end and closed at the other end and having a fuse terminal adjacent said closed end, a conductive mount secured to said holder in conductive relation to said terminal, a second conductive mount secured to the holder adjacent the open end of said tube and having a terminal clamp for one end of a fuse link extending from the open end of the tube, said mounts having clamping means for clamping attachment thereof respectively to conductors for supporting said holder and each of the mounts including at least two relatively stiff elements articulated for relative movement so as to provide for adjustment of the positional relationship between the said conductor clamping means of the two mounts, said second mount being substantially longer than said first mount, and a fuse link tensioning and retracting spring device mounted on said second mount for engagement with a portion of a fuse link extending from the open end of the tube, said device having a part movable to a readily observable indicating position upon fuse operation.

4. In a fuse device for suspension mounting directly on the conductors of an electric line, an insulating tubular fuse holder open at one end and having fuse terminal means adjacent the other end, a conductive mount secured on said holder in conductive relation to said terminal means, a second conductive mount secured on said holder adjacent the open end thereof, each of said mounts including a metallic hanger pivotally attached at one end to a metallic strap which is. bent so as to extend around said holder and which strip is quick detachably secured to the holder, the other end of each of said hangers having clamping means for attachment to an electric line conductor, and a terminal clamp on said second mount for securing thereto one end of a fuse link extending out of said open end of said holder.

SIDNEY R. SMITH, JR. 

